MCQ on Fluorescence spectroscopy: Page-1

Fluorescence intensity is reduced by

(P) Intersystem crossing (Q) Vibrational relaxation

(R) Conjugation (S) Molecular planarity.

(A) P,R

(B) P,Q

(C) R,S

(D) Q,S

Which of the following factors increases fluorescence intensity.

(A) Electron withdrawing group

(B) Photo decomposition

(C) Increase in temperature

(D) Increase in viscosity.

Fluorescence quenching is

(A) Conversion of fluorescence to phosphorescence

(B) Enhancement of fluorescence

(C) Absence of fluorescence

(D) Repression of fluorescence

The fluorescence spectroscopy has

(P) High sensitivity (Q) Low sensitivity (R) High specificity (S) Low specificity

(A) P,S

(B) Q,R

(C) P,R

(D) Q,S

The selectivity and sensitivity of fluorescence spectroscopy is higher than that of absorption spectroscopy because of all of the following EXCEPT

(A) Fluorescence substance have different λmax of excitation and emission

(B) Rigid molecules can only fluoresce

(C) Florescence intensity depends on the intensity of the incident radiation

(D) Every molecule that absorbs in UV region can show fluorescence